Process for preparing high-reactivity isobutene homo- or copolymers

A process for preparing high-reactivity isobutene homopolymers or copolymers with a content of terminal vinylidene double bonds per polyisobutene chain end of at least 70 mol %, the process comprising:

• polymerizing a monomer comprising isobutene in the presence of a Lewis acid polymerization catalyst comprising (a) an aluminum trihalide-donor complex, an alkylaluminum halide-donor complex, an iron trihalide-donor complex, a gallium trihalide-donor complex, a titanium tetrahalide-donor complex, a zinc dihalide-donor complex, a tin dihalide-donor complex, and/or a tin tetrahalide-donor complex (b) a mixture comprising an organic compound (II) comprising an oxygen or nitrogen atom with at least one lone electron pair, and (c) an ionic liquid,
• thereby obtaining the high-reactivity isobutene homopolymers or copolymers having a number-average molecular weight in a range of from 500 to 10,000, determined by gel permeation chromatography, and having the content of the terminal vinylidene double bonds per polyisobutene chain end of at least 70 mol %.